 Evolution

1. Evolution • In science, theories are statements or models that have been tested and confirmed many times. • Theories have some important properties: • Explain a wide variety of data and observations • Used to make predictions • Not absolute, they serve as a model of understanding the world and can be changed as the world view changes

2. Questions??? • Why do so many different animals have the same structures, the arm bones in a human are the same bones as a flipper in a whale? • Why do organisms have structures they no longer use, like the appendix in a human? Non functioning wings in penguins • Why are there bones and fossil evidence of creatures that no longer exist? What happened to these creatures? • Why do the embryos of animals look very similar at an early stage?

3.  Lamarke's Theory • Some thought that you would gain or lose features if you overused or didn't use them, and you could pass these new traits onto your offspring. • Known as the Inheritance of Acquired Characteristics • A lizard that didn't use it legs would eventually not have legs and its offspring wouldn't have legs • A giraffe stretched its neck to reach higher leaves, and this stretched neck would be a trait inherited by its offspring

4. Lamarke's Theory • Lamarke's Theory was eventually discarded - PROVEN TO BE WRONG! • Why? Logically it doesn't work. Imagine if you were in a car accident and had a leg amputed. This does not mean that your children will only have one leg. Features gained during life are not passed on to children.

5.  Darwin's Theory • - Naturalist • traveled to the Galapagos Islands on the HMS Beagle • his observations of the finches (and other animals) • noted that all the finches looked about the same except for the shape of their beak. • conclusion that all the finches were descendents of the same original population • The shape of the beaks were adaptations for eating a particular type of food (Ex. long beaks were used for eating insects, short for seeds)

6. Darwin’s Finches

7.  "The Origin of Species” 1. Variation exists among individuals in a species. 2. Individuals of species will compete for resources (food and space) 3. This competition leads to the death of some and survival of others - Survival of the Fittest 4. Individuals with advantageous variations - more likely to survive and reproduce.

8.  This process by which populations change in response to their environment is known as Natural Selection . Natural Selection can be said to be a result of Adaptive Radiation-This is where species all deriving from a common ancestor have over time successfully adapted to their environment. Ex: finches- the finches adapted to take advantage of the various food sources available on the island, which were being used by other species. Over the long term, the original finch species may have disappeared, but by diversifying, would stand a better chance of survival. The favorable variations are called Adaptations-leading to increased survival rate.

9.  Evidence of Evolution • Fossil Evidence • Carbon dating--gives age of a sample based on the amount of radioactive carbon is in a sample. • Fossil record--creates a geologic time scale. • Biochemical Evidence - Amino acids-Proteins • Nucleic acids- DNA

10.  Evidence of Evolution Anatomy and Development • Homologous Structures- are embryologically similar, but have different functions, the wing of a bird and the forearm of a human

11.  Evidence of Evolution • Vestigial Organs/structures--seemingly functionless parts, snakes- tiny pelvic and limb bones • Humans - tail bone; appendix

12.  Evidence of Evolution • Embryological development--Embryos of different species develop almost identically

13.  Evidence of Evolution cont. Convergent evolution- organisms of different species evolve similar features independently usually because they live in the same environment • Bird wings and insect wings Divergent evolution- organisms of the same species adapt differently because they live in different environments - shells of Galapagos tortoises; beaks of finches

14.  Rate of Evolution • Gradualism • Gradual change over a long period of time • Punctuated equilibrium • Period of rapid change in species separated by periods of little or no time

15. Examples of Evolution • industrial melanism (Kettlewell's moths) • dog breeds • viruses & vaccines • bacteria & antibiotics